99e075ff29
Add -Z normalize-docs and enable it for compiler docs Works around https://github.com/rust-lang/rust/issues/79459 by only enabling normalization for the compiler itself (and anyone who opts-in on nightly). Eventually I want to remove this and enable normalization by default, but that's turned out to be [really hard](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/How.20do.20I.20normalize.20projection.20types.20to.20a.20single.20type.3F/near/218125195). This uses a command line option instead of a feature gate so it's easier to pass it to all crates at once. Theoretically it's better to use a feature gate instead so that it's easier for people to use on docs.rs, but I'm also not terribly concerned with how easy it to use a temporary hack. Addresses https://github.com/rust-lang/rust/issues/77459.